Chapter 19 The Heart 61-90

Pacemaker cells isolated from the SA node generate action potentials at ________ beats per minute.

80-100

The first heart sound is heard when the

AV valves close.

A heart murmur might be caused by

All

Which of the following would increase heart rate?

All

Considering the left ventricle, why does isovolumetric ventricular contraction occur during ventricular systole?

Aortic pressure is higher than ventricular pressure and the ventricle must pressurize the blood to open the aortic valve.

If the pacemaker cells in the SA node become more permeable to potassium ions, the

heart rate will decrease and cells will hyperpolarize

Depolarization of the atria corresponds to the EKG's

P wave.

The T wave on an ECG tracing represents

ventricular repolarization

At a heart rate of 60 beats/minute, a cardiac cycle lasts

1 second

The systolic part (both atrial and ventricular) of a cardiac cycle lasts, on average

370 msec

In what order would excitation move through the conducting system of the heart? 1. Purkinje fibers 4. SA node 2. AV bundle 5. bundle branches 3. AV node

4, 3, 2, 5, 1

During ventricular systole, the

AV valves are closed

________ is to slow heart rate as ________ is to fast heart rate

Bradycardia; tachycardia

Depolarization of the ventricles is represented on an electrocardiogram by the

QRS complex.

With each ventricular systole

blood pressure increases

An increase in the rate of action potentials from baroreceptors will trigger a reflex to

both decrease heart rate and decrease pressure

During the T wave of the electrocardiogram, the ventricles are

both repolarizing and relaxing

Pacemaker cells in the SA node

can spontaneously depolarize.

The first heart sound ("lubb") is associated with

closing of the atrioventricular valves

The P wave of the electrocardiogram is a signal from

depolarization of the atria.

Each of the following factors will increase cardiac output except increased

parasympathetic stimulation.

Analysis of the electrocardiogram can reveal all of the following except

stroke volume

The volume of blood ejected from each ventricle during a contraction is called the

stroke volume

The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the

systolic ejection phase

As a result of the long refractory period in the cardiac action potential, cardiac muscle cannot exhibit

tetany.

If the connection between the SA node and AV node becomes blocked,

the ventricles will beat more slowly

The following are structural components of the conducting system of the heart. 1. Purkinje fibers 2. AV bundle 3. AV node 4. SA node 5. bundle branches The sequence in which excitation would move through this system is

4, 3, 2, 5, 1.

Abnormally slow depolarization of the ventricles would most change the shape of the ________ in an ECG tracing.

QRS complex

"An increase in end-diastolic volume increases the stroke volume" is a way of stating ________ law of the heart.

Starling's

If there is a complete block between the SA node and the AV node, how would the ECG be affected?

The rate of P waves will be faster than the rate of QRS complexes